Fabric for toothed power transmission belt and belt

ABSTRACT

A fabric for reinforcing a power transmission belt including fibers of polyarylene sulfide and a belt utilizing the fabric. The fabric may have textured or elastic core wrapped stretch yarns in the longitudinal direction. Longitudinal yarns may include PPS and textured transverse yarns include nylon. Yarns may include blends of high performance fibers and nylon or other fibers.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates generally to a toothed power transmission belt,more particularly to a toothed belt with a heat and wear resistantfabric for tooth support, and specifically to a toothed belt with toothsupport fabric including fibers of poly p-phenylene sulfide.

Description of the Prior Art

Toothed power transmission belts are used in synchronous belt drives.Toothed belts commonly have an elastomeric body with a layer ofreinforcing tensile cords which provide high dimensional stability. Thebody under the cord layer is formed into a series of teeth which mesh inpulleys or sprockets and transmit drive loads to the tensile cord. Theteeth are commonly covered with a reinforcing fabric such as a wovenstretch fabric of nylon-66 multi-filament yarns. Tooth reinforcingfabrics may be of plain or twill weave or the like. Fabric layers mayalso be used on the backside of toothed belts, on the backside or pulleycontacting profile of multi-v-ribbed belts, or in v-belts or flat belts.Nylon-66 (also known as polyamide-66 or PA-66) fabrics commonly utilizetextured or crimped yarns in one direction, as described for example inU.S. Pat. No. 4,826,472 which is hereby incorporated herein byreference, to allow sufficient stretch in the longitudinal direction ofthe belt to conform to the teeth during a flow-through beltmanufacturing process, as described for example in U.S. Pat. No.3,078,206 which is hereby incorporated herein by reference. Otherfabrics utilize elastic core yarns to achieve sufficient stretch in thelongitudinal direction, as described for example in U.S. Pat. No.5,529,545 which is hereby incorporated herein by reference. These yarnswill be called hereinafter the “longitudinal yarns” of the beltlengthwise direction, whereas the yarns to be combined with thelongitudinal yarns will be called the “transverse yarns”. However, these“longitudinal yarns” and “transverse yarns” are not necessarilycoincident with the terminology “warp” and “weft”, as used to describethe textile structure.

Increased demands on power transmission belts, particularly in the areaof automotive under-hood applications, have lead to a number of fabricvariations intended to improve the performance of power transmissionbelts, including for example, use or substitution of para-aramid,meta-aramid, polyetheretherketone (PEEK), polyimide (PI), orpolytetrafluoroethylene (PTFE) yarns or fibers in place of some or allof the usual nylon weft yarns or fibers, for example as disclosed in WO2006-066669. Each proposed variation has limitations, so new fabricalternatives are yet desirable. One problem is that PEEK, aramid, andPTFE are not as easily bonded to elastomer belt body compositions asnylon is, so only limited amounts of substitution for nylon in the weftare practical such as disclosed in WO 2006-066669. Another problem isthat para-aramid cannot be textured like nylon, so other means ofimparting stretch to some longitudinal yarns must be used, such ascombining aramid with elastic yarn as described for example in U.S. Pat.No. 5,529,545. Such combined yarns may suffer from decreased properties.Many such high-performance yarns and fabrics may be limited in use byeconomic considerations.

What is needed is a stretch fabric for power transmission belts havinghigh heat, fluid, flex, and abrasion resistance, but at a much morereasonable cost than other proposed solutions. What is needed is afabric which can be processed like conventional nylon-66 stretchfabrics. What is needed is a fabric with good adhesion to elastomericmaterials used in belts. The present invention meets one or more ofthese needs.

SUMMARY

The present invention is directed to systems and methods which provide apower transmission belt with a high heat, fluid, and abrasion resistantreinforcing fabric, for example covering a tooth surface or a beltbackside. The present invention also provides a reinforcing fabric for apower transmission belt.

The present invention is directed to a power transmission belt having anelastomeric body, tensile cord reinforcing member, and reinforcingfabric member. The invention is also directed to a reinforcing fabricfor a power transmission belt. In one embodiment, the reinforcing fabricmember comprises a yarn, thread, or fiber of a polyarylene sulfidematerial. The fabric may be woven or non-woven fabric. A preferredpolyarylene sulfide material is poly(p-phenylene sulfide) (“PPS”). ThePPS fiber, thread, or multifilament yarn may replace some or all of thenylon-66 fiber, thread or yarn in the longitudinal yarns of aconventional woven belt fabric. The PPS fiber may be present in the weftor warp yarns of the fabric, but is preferably present at least in thelongitudinal yarns of the belt fabric. Preferably the longitudinal yarnscontaining the PPS are textured to provide stretch in the longitudinaldirection. The transverse yarns may be textured. The weft may be thelongitudinal direction and the warp the transverse direction.

The belt may be a toothed belt, a flat belt, a v-belt, or multi-v-ribbedbelt. The fabric may cover the teeth or other pulley contact surface ofthe belt, or the fabric may cover the backside or be embedded in theelastomeric belt body.

The fabric may have a transverse yarn including textured nylon-66 fibersor yarns. The fabric may be treated to promote adhesion to theelastomeric body.

By utilizing PPS fibers in the fabric according to the presentinvention, the fabric is rendered more heat resistant, oil resistant,and wear resistance than conventional nylon-66 fabric. Thus, theinvention provides a more durable and heat, fluid and wear resistantbelt for a reasonable cost differential.

The present invention is also directed to a power transmission belthaving a reinforcing fabric and a reinforcing fabric for a powertransmission belt wherein the reinforcing fabric includes longitudinalyarns capable of stretching, preferably at least about 50% or at leastabout 80%, and transverse yarns having textured multifilament nylonfibers. At least a portion of the longitudinal yarns have nylon fibersand fibers of one or more selected from the group consisting ofpara-aramid, meta-aramid, polyester, polyketone, polyimide,polyacrylonitrile, polysulfonamide, acrylic, fluoropolymer, andpolyarylene sulfide. By utilizing textured nylon fibers in thetransverse yarns, adhesion of the fabric to the belt body may beimproved and/or penetration of treatments into the fabric may beimproved. In various embodiments, the longitudinal stretch yarns may betextured blended yarns of the aforementioned materials, or elastic coreyarns wrapped with the aforementioned materials.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present invention. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe spirit and scope of the invention as set forth in the appendedclaims. The novel features which are believed to be characteristic ofthe invention, both as to its organization and method of operation,together with further objects and advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form part ofthe specification in which like numerals designate like parts,illustrate embodiments of the present invention and together with thedescription, serve to explain the principles of the invention. In thedrawings:

FIG. 1 is a partially fragmented perspective view of a toothed beltconstructed in accordance with an embodiment of the present invention;

FIG. 2 is a representation of a portion of fabric constructed inaccordance with an embodiment of the present invention;

FIG. 3 is a representation of portions of yarns utilized in embodimentsof the present invention;

FIG. 4 is a representation of a portion of a stretch yarn utilized inembodiments of the present invention; and

FIG. 5 is a schematic of a belt and pulley system utilizing anembodiment of the present invention.

DETAILED DESCRIPTION

The invention relates to a fabric useful for a power transmission beltand the resulting belt. FIG. 1 shows a partially fragmented perspectiveview of a toothed belt constructed in accordance with an embodiment ofthe present invention. In FIG. 1, toothed belt 10 has a elastomeric bodywhich includes elastomeric back 12, elastomeric tooth 16, and embeddedtensile member 18. Tooth reinforcement fabric 14 covers tooth portions17 and land portions 19 and is the pulley contact surface of the toothedbelt. According to an embodiment of the invention, fabric 14 comprisesfibers of a poly(arylene sulfide) (“PAS”) polymer. Preferably the PASpolymer is poly (p-phenylene sulphide) (“PPS”). FIG. 2 shows a 2×2 twillwoven fabric according to an embodiment of the present invention. Wovenfabric 20 is formed from warp yarns 22 and weft yarns 24. When used asthe reinforcement fabric 14 for belt 10, either the warp or weft may beoriented in the longitudinal direction of the belt (i.e. generallyparallel to tensile member 18), while the other is oriented in thetransverse direction of the belt (i.e. generally perpendicular totensile member 18). The PAS or PPS fibers may be present in fabric 14 inthe longitudinal direction, the transverse direction, or both directionsof the belt.

A belt according to an embodiment of the invention is typically used ina belt drive system, which may include at least a belt, a driver pulleyand a driven pulley. FIG. 5 illustrates a belt drive system having belt10, driver pulley 56 and driven pulley 58.

An embodiment of the present invention is a fabric for reinforcing apower transmission belt comprising fibers of PAS. PAS polymers suitablefor fibers for use in practice of the invention may be homopolymers,copolymers, terpolymers and the like or a blend of polymers. Examples ofpolyarylene sulfide polymers include poly(2,4-toluene sulfide),poly(4,4′-biphenylene sulfide), and poly(p-phenylene sulfide) (“PPS”).Because of its availability and desirable properties, PPS fibers arecurrently preferred. Suitable PPS fibers include: Sulfar Fiber soldunder that trade name by Testori Group; Diofort® multifilament PPS yarnfrom Diolen Industrial Fibers; and Procon PPS fiber sold under thattrade name by Toyobo Co. Ltd. Commercial polyarylene sulfide fiber isbelieved to be a synthetic fiber in which the fiber-forming material isa long chain synthetic polysulfide in which at least 85% of the sulfidelinkages are attached directly to two aromatic rings. PPS may be formedby reaction of sulfur with dichlorobenzene and then extruded by meltspinning to produce staple or filament fibers. PPS is a crystallinepolymer having a symmetrical, rigid backbone chain of recurringpara-substituted benzene rings and sulfur atoms.

In various embodiments, the fabric may be woven or non-woven fabric. Asuitable woven fabric may have warp and weft threads, and at least oneof said warp and weft threads includes a multifilament yarn of PASfibers, or preferably PPS fibers. The fabric may further includenylon-66 fibers. In one embodiment, the fabric has PPS fibers present inthe weft, and the warp includes or consists essentially of texturednylon-66. Preferably, for use in a belt, the PPS is present inlongitudinal yarns and the transverse yarns include or consistessentially of textured nylon-66. The longitudinal yarns may includeboth nylon-66 and PPS fibers and may be textured.

In various embodiments, a power transmission belt may be a toothed belt,a flat belt, a v-belt, or multi-v-ribbed belt. The fabric having fibersof PAS, or preferably PPS, may cover teeth or other pulley contactsurface of a belt, or the fabric may cover the backside or be embeddedin the elastomeric belt body. Various examples of belts and fabricswhich may advantageously be adapted by incorporating PAS fiber accordingto an embodiment of the invention may be mentioned without intending tolimit the invention. U.S. Pat. No. 6,793,599, which is herebyincorporated herein by reference, describes V-belts and multi-v-ribbedbelts having pulley engaging non-woven regions wherein the non-wovenmaterial may include synthetic fiber material. U.S. Pat. No. 5,529,545,incorporated herein by reference, describes toothed belts with stretchfabric for use in a flow-through manufacturing process. Usefulembodiments of the fabric of the present invention may also includenon-stretch or semi-stretch fabrics for covering the teeth of toothedbelts in a pre-form manufacturing process or for covering V-belts orbelt backsides where little stretch is needed. Knit fabrics and beltsusing knit reinforcements as disclosed for example in U.S. Pat. Nos.5,645,504 and 6,863,761, which are hereby incorporated herein byreference, may be usefully improved according to an embodiment of thepresent invention.

Typical automotive synchronous or toothed belts use 100% nylon fabricwith adhesive coatings as the cover element on the belt teeth. In oneembodiment, the present invention relates to a tooth fabric with hybridconstruction consisting of nylon fibers and other fibers having greaterheat and/or oil resistance and or other high performance characteristicrelative to nylon. In certain embodiments of the invention, the otherfibers may be of a high performance polymer which may be difficult tobond to elastomeric materials such as utilized in the body of a belt.The heat and/or oil resistant fibers may be incorporated by combiningthreads or fibers of these materials with nylon or other conventionalmaterial within one or more weft or longitudinal yarns of the fabric.Warp or transverse yarns may be 100% nylon, but unlike conventionalnylon fabrics, the warp or transverse yarns are textured to provide ahigher degree of coverage and penetration by the subsequent RFL or otheradhesive coating. Improved penetration of coating into the fabric mayprovide improved protection against fatigue and/or abrasion.

Thus, another embodiment of the invention is a woven fabric forreinforcing a power transmission belt having longitudinal yarnspreferably capable of stretching at least about 80% and transverse yarnshaving textured multifilament nylon yarn preferably capable ofstretching from about 1% to about 20% at 2 kg tension, with at least aportion of the longitudinal yarns including nylon fibers and fibers ofone or more high performance materials, which may be relatively hard tobond to elastomers, such as para-aramid, meta-aramid, polyester,polyketone, fluoropolymer, polyimide, polysulfonamide, polyarylenesulfide, acrylic, and the like.

The stretching capability of the woven fabric may be provided bytexturing the longitudinal yarns. Texturing is generally a possibilityfor thermoplastic fibers such as polyester, polyketone, polyarylenesulfide and the like, either separately or along with nylon fibers.Texturing may be achieved by any known texturing method, such as falsetwisting, crimping, stuffer box, knit-de-knit, air jet, and the like.The elongation of the textured yarn is a way of characterizing thedegree of texturing. In particular, the elongation at a specified load,such as 2 kg, may provide a useful measure of the degree of texturing ofa yarn. Textured longitudinal yarns for tooth covering fabric for atoothed belt preferably is capable of at least about 50% elongation at 2kg tension, or at least about 80% elongation at 2 kg tension.

Alternately, the stretching capability of the woven fabric may beprovided by using for the longitudinal yarns an elastic core threadwrapped with nylon and one or more selected high performance fibers. Forexample, the selected high performance fibers may be used in at least afirst wrap about the elastic core and nylon-66 fibers in at least asecond wrap. It may be advantageous for the second wrap to be in theopposite wrap direction from the first wrap. Examples of such stretchyarn constructions are provided in U.S. Pat. No. 5,529,545, EuropeanPat. No. 637,704, and European Pat. No. 1,436,450, which are all herebyincorporated herein by reference. FIG. 4 illustrates such a stretchyarn. Referring to stretch yarn 45 in FIG. 4, elastic core 46 is firstwrapped in a first direction with yarn 47 which may advantageouslyinclude PAS or PPS, and is second wrapped in the opposite direction withyarn 48 which may be of nylon.

The texturing of the transverse yarn may be achieved in the same manneras described above for the longitudinal yarn. In an embodiment of theinvention, the degree of texturing of the transverse yarn may besubstantially less than that of the longitudinal yarn. The elongation at2 kg of the longitudinal yarn, for example, may be greater than about50%, or greater than about 80%. The elongation at 2 kg of the transverseyarn may be in the range from about 1% to about 15%, or from 2% to about10%. Higher stretch in the longitudinal direction is useful formanufacture of toothed belts by the flow through process, during whichthe fabric stretches from following the tensile member line to form theentire profile of the teeth. Less stretchy yarn in the transversedirection is sufficient for providing the above mentioned benefits oftexturing in that direction. In an embodiment of the invention, thetransverse yarns may consist essentially of textured multifilament nylonyarn, preferably nylon-66. The above mentioned fabric may also be usedin a power transmission belt.

By way of example, FIG. 3 shows a representative length of arepresentative longitudinal highly textured yarn, a transverse lightlytextured yarn useful in an embodiment of the present invention, and anon-textured yarn. Referring to FIG. 3, highly textured yarn 34 exhibitsan elongation of about 88% at 2 kg tension. Lightly textured transverseyarn 32 exhibits an elongation of about 3% at 2 kg tension. Elongationat break for non-textured yarn 30 is about 25% at about 100 kg, and forlightly textured yarn 32 is about 30% at 104 kg. Elongation at break forthe highly textured yarn 34 is about 180% at 323 kg. The break strengthis higher because yarn 34 has about three times more filaments than yarn30 or 32.

The respective high performance yarns or fibers may be commingled,co-plied, or co-twisted at any stage of the yarn or cord manufacturingprocess with conventional yarns or fibers which may preferably be ofnylon, or which may be of acrylic, polyester, cotton, and the like. Itshould also be noted that there may be blended at any ratio a thirdhigh-performance or heat-resistant yarn along with the firsthigh-performance yarn and nylon. Staple yarns may also be used or ablended staple yarn containing fibers including PEEK, PPS, and/orothers.

By nylon is meant any thermoplastic polyamide fiber including nylon-6,nylon-66, nylon-46, and the like. Nylon-66 is a preferred polyamide.Nylon-66 may moreover be of a high tenacity variety or medium or normaltenacity.

By aramid is meant a long chain synthetic polyamide having its amidelinkages attached directly to two aromatic rings in either the para ormeta position. In the present invention, use may be made, for example,of PPD-T, poly(p-benzamide), copoly(p-phenylene/3,4′-oxydiphenyleneterephthalamide), or the like. By PPD-T is meant the homopolymerresulting from mole-for-mole polymerization of p-phenylene diamine andterephthaloyl chloride and, also, copolymers resulting fromincorporation of small amounts of other diamines with the p-phenylenediamine and of small amounts of other diacid chlorides with theterephthaloyl chloride. Commercial aramid fibers suitable for thepractice of this invention include those sold under the trademarksTEIJINCONEX, TECHNORA, and TWARON by Teijin Limited, and under thetrademarks NOMEX, and KEVLAR by E.I. DuPont de Nemours and Company.

A suitable commercial LCP fiber is the liquid crystalpolyester-polyarylate fiber sold under the trademark VECTRAN by CelaneseAcetate LLC and Kuraray Co., Ltd. PBO is sold under the trademark ZYLONby Toyobo Co., Ltd. Polyester fibers include polyethylene terephthalate(PET) and polyethylene naphthalate (PEN). PEN is sold under thetrademark PENTEX by Honeywell International Inc. PEN is also sold byTeijin Limited, INVISTA, and Hyosung Corporation.

Suitable fluoropolymers may include for example but are not limited topolytetrafluoroethylene polymer (PTFE), polytrifluoromonochloroethylenepolymer (PTFCE), polyvinylidene fluoride polymer (PVDF), fluorinatedethylene polymer (FEP) and perfluoroalkoxy polymer (PFA).

Polyimide and/or polyamide-imide fibers (“PI”), especially hightemperature polyimides, may be used. A suitable PI fiber may be P84,sold under that trade name by Inspec Fibres, a Degussa company.Polyacrylonitrile (“PAN”) fibers are sold, for example, by Toyobo Co.Ltd. PAN fibers include fibers with a range of acrylic content,generally at least 85% acrylonitrile, and various comonomers, such asmethyl methacrylate, vinyl acetate, and the like.

Polysulfonamide (“PSA”) fiber is a kind of aromatic polyamide fiberhaving a main chain of benzene rings para-linked with SO₂ groups andamide linkages. PSA fiber is currently sold in staple form under thetrade name Tanlon by Shanghai Tanlon Fiber Co., Ltd. The characteristicsof PSA include high temperature resistance, excellent flame resistance,dimensional stability at high temp, and high chemical stability.

Polyketone fibers are formed from polymers having ketone bonds or groupsin the main chain. For example, U.S. Pat. No. 5,130,408 describes anumber of types or aromatic polyketones including polyetherketones(PEK), polyetheretherketones (PEEK), polyetherketoneketones (PEKK), andpolyaryletherketones (PAEK) which may be advantageously used in thepresent invention. One example of a commercial PEEK material has arepeat unit of oxy-1, 4-phenyleneoxy-1, 4-phenylene-carbonyl-1,4-phenylene which forms a linear aromatic semi-crystalline polymer withvery high temperature resistance. A suitable PEEK fiber is sold underthe trade name Zyex by Zyex Ltd.

Another useful polyketone fiber may be formed from polyketone polymerhaving an intrinsic viscosity of about 5.9 dl/g in which ethyleneprepared by a conventional procedure is completely copolymerized withcarbon monoxide and poly (1-oxotrimethylene). In general, usefulpolyolefin ketone (POK) fiber can be obtained by melt spinning or wetspinning as disclosed in U.S. Pat. No. 6,763,867 and references citedtherein. It may be advantageous to use a polyolefin ketone fiber havinga structure represented by the following formula:¬—(CH2-CH2-CO)n-(R—CO)m- where, 1.05>=(n+m)/n>=1.00, and R is analkylene group having three or more carbons as described in U.S. Pat.No. 6,763,867. The POK fiber may advantageously be of an alternatingpolymer of carbon monoxide and ethylene as described in U.S. Pat. No.6,818,728. All of the above types of polyketone fibers will be referredto as “PK” or polyketone herein and in the claims.

Table 1 lists a number of high performance fibers which may beadvantageously applied in embodiments of the present invention, alongwith some typical properties. In the table, “−” means poor, “0” meansfair, “+” means good, and “++” means excellent. Also in the table, “MR”is moisture regain; “m.p.” is melting point; “HAS” is heat agedshrinkage; and “Eb” is elongation at break.

TABLE 1 meta- Polymer PA 66 PPS PPS aramid PI PEEK PEEK PAN PTFE PSAfiber type Contin- Contin- Contin- Contin- Contin- Contin- Contin-staple Contin- staple uous uous uous uous uous uous uous uous Trade nameDiofort Tanlon Maker Diolen Toyobo Inspec generic Zyex Toyobo GoreShanghai filament 4 0.6-8 0.9-8   1.2-4 size, dtex tenacity, 79.5 >52 4040-45 (35) 20-40 62 60-70 >30 cN/tex Eb, % 25 20-25 25 20 1.5-2   HAS, %<1 or 5 3.5 1.1 1.5-2   use temp ° C. 95 190 190 190 (240) 250 250 125250 250 continuous Density 1.14 1.35 1.35 1.38 1.3 1.18 2.18 1.42 m.p. °C. 255 290 290 334 MR, % 4.5 <0.02 4-5 (3) 0.1 0 6.3 resist to 0 0 0 +(+) 0 0 ++ oxidation resist to − ++ ++ 0 (+) ++ ++ ++ hydrolysis resistto acid 0 ++ ++ 0 (+) + + ++ + resist to − ++ ++ + (0) + + ++ 0 alkalis

In the construction of a belt according to an embodiment of theinvention, the generally flexible material or materials utilized in theovercord section 12 and teeth 16 should generally be compatible with oneanother and may be of the same or of different types of material. Anysuitable and/or conventional elastomer, including both castable andnon-castable elastomers, may be used as the overcord 12 and/or the teeth16 (hereafter collectively, “the belt body portions”) in this embodimentof the present invention. Examples of suitable castable elastomersinclude but are not limited to castable polyurethanes (includingpolyurethanes, polyurethane/ureas and polyureas), plastisols,organosols, liquid chloroprenes, liquid polysulfides, liquid rubbers,silicones, epoxides, urethanes, polyester based resins, polyether basedresins, and the like, as well as blends of any two or more thereof.Polyurethane elastomers are generally preferred over other types ofcastable elastomers at present because of their favorable tensilestrength and abrasion resistance and their satisfactory modulus andelasticity. Such polyurethanes may be prepared in any conventionalmanner, such as by compounding a polyurethane prepolymer with a chainextending agent, and optionally an amount of plasticizer or otheringredient if desired. Conventional chain extenders may be utilized,which are generally known to the art.

Non-castable elastomers useful as the belt body portions of such beltsthat would likely enjoy the benefits provided by the present inventioninclude for example, chloroprene rubber (CR), acrylonitrile butadienerubber (NBR), hydrogenated NBR (HNBR), styrene-butadiene rubber (SBR),alkylated chlorosulfonated polyethylene (ACSM), epichlorohydrin,butadiene rubber (BR), polyisoprene (including both natural rubber (NR)and synthetic polyisoprene) and ethylene-alpha-olefin elastomersexemplified by ethylene propylene diene terpolymer elastomer (EPDM), aswell as blends or mixtures of any two or more of the foregoing. Mostthermoplastic elastomers are also envisioned within this context.Continuous or long-length belts, for example formed by extrudingthermoplastic elastomer onto cord and fabric and pressing onto arotating mold, are also envisioned within this context.

Whether a castable or non-castable elastomer is utilized in thecompositions to form the elastomeric portion(s) of the belt, suchcompositions may also generally include conventional additives inamounts generally suitable for use in the intended application. Thus forexample, such composition may also include a reinforcing, partiallyreinforcing or non-reinforcing filler in amounts of from about 0 partsper hundred weight of rubber (phr) to about 500 phr; alternatively offrom about 20 phr to about 250 phr; one or more plasticizers in amountsof from about 0 phr to about 30 phr, or alternatively of from about 1phr to about 25 phr; one or more vulcanization agents or curatives,including sulfur, free-radical-generating materials such as peroxide andionizing radiation, etc., in cure-effective amounts of, e.g., from about0 phr to about 30 phr for example; one or more co-agents or activatorsin amounts of from about 0 to about 100 phr; and one or moreantidegradants in amounts of from about 0 phr to about 15 phr etc. Inone embodiment of the present invention at least one of the overcordportion 12 and the teeth 16 of the belt 10 are formed of a suitablehydrogenated acrylonitrile butadiene rubber (HNBR) composition such asthat set forth for example in U.S. Pat. No. 6,358,171, to Whitfield, thedisclosure of which with regard to such elastomer compositions is herebyincorporated by reference; or a suitable polyurethane/urea compositionsuch as that set forth for example in WO09602584 to Wu et al., thedisclosure of which with regard to such elastomer compositions is herebyincorporated by reference.

The elastomer overcord section 12 is preferably provided with areinforcing tensile layer or a plurality of tensile members, any numberof which are well known to the art, such as the longitudinally extendingand spaced tensile cords 18 as shown. These tensile cord 18 may consistof one or more strands of any suitable strain-resistant materialincluding but not limited to polyamide cord, aramid cord, glass fibercord, carbon fiber cord, polyester cord, or filament wire cord, orhybrids or combinations thereof, typically disposed as one or moreembedded helically-wound cords as shown. The tensile members may bepre-stressed or impregnated or coated with a suitable adhesive orprocess-aid material, particularly where a non-castable elastomer suchas HNBR is employed as or in the belt body portion.

The flexible materials forming the teeth 16 and/or overcord 12 portionsmay optionally be loaded with discontinuous fibers, by the incorporationwithin the elastomer composition while generally in the un-vulcanizedstate of any suitable and/or conventional material including staplefiber, pulp fiber or chopped fiber reinforcement materials. Suitablematerials for fiber loading include for example aramids, including meta-and para-aramids, such as those available by DuPont Chemical Co. underthe trademark, KEVLAR; nylon, polyester, acrylic, carbon, and cotton.Fiber loading may be at any level suitable for the application, such asthat disclosed in U.S. Pat. No. 6,358,171, the disclosure of which withregard to such fiber loading types and levels is hereby incorporated byreference; and may include in the case of toothed belts orientation ofat least a substantial number of the fibers in a direction perpendicularto the travel of the belt. One or more such fibers may moreover protrudefrom the elastomeric material.

The generally wear-resistant fabric layer 14, or fabric 20 intimatelyfits along the power transmitting surface of the belt 10, which is inthe case of the toothed belt illustrated in FIG. 1, along at least thealternating teeth 16 and land portions of the belt 10 as shown, to forma cover therefor. The fabric utilized may be of any desiredconfiguration such as a conventional weave consisting of warp and weftthreads at any desired angle, including such weaves as twill-, square-or matte woven 1×1, −1×2, −1×3, −2×1, −2×2, −2×3, −3×1, −3×2, or −3×3fabrics; or may comprise pick cords, or be of a knitted or braidedconfiguration, or of a nonwoven configuration, or the like. More thanone ply of fabric may be employed, including combinations of differenttypes of fabrics. If desired, the fabric may be cut on a bias as is wellknown in the art so that the strands form an angle with the direction oftravel of the belt. Conventional fibers may be employed such as cotton,polyester, polyamide, aromatic polyamide, hemp, jute, fiberglass andvarious other natural and synthetic fibers.

In an embodiment of the invention, the fabric layer 14 comprises abias-cut 2×2-twill or -matte woven fabric. At least one of the warp orweft yarns may moreover be scoured, heat-set, textured, twisted, and/orotherwise processed as are each well known in the art. Optionally, thesurface of the belt remote from its power transmitting surface may alsoinclude a fabric element as herein described, (hereafter, “back fabric”)which back fabric may be either of the same type and form as thatutilized along tooth portion 17 and land portion 19 of the belt 10, orof a different type or form.

In an embodiment of the present invention an amount of internallubricating agent may be utilized upon and/or within the fabric coverelement. A lubricant may be included in a fabric treatment, such as RFL,or applied in a separate lubricating treatment. Examples of use oflubricants for belt fabrics are disclosed for example in U.S. Pat. No.7,042,021 and U.S. Publication No. 2007/249451, the contents of whichare hereby incorporated herein by reference.

Examples may be built and tested to demonstrate the usefulness andadvantages of the embodiments of the present invention. Descriptions ofthe belt tests are as follows:

Max force test (air environment) uses a 120-tooth belt, 30-mm widetested on ultra high load diesel motored engine. The engine speed isvaried throughout the course of the test, to exert the maximum load onthe belt. The test is conducted at ambient temperature.

High temperature test (air environment) uses a 141-tooth belt, 15-mmwide tested on high load diesel motored engine. The engine is maintainedat a constant speed of 4000 rpm. Flow of fuel to the injection pump isregulated at 480 ml/min. The test is conducted in a hotbox, with heatinput controlled such that the belt temperature is 200° C.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps. The invention disclosed herein may suitably bepracticed in the absence of any element that is not specificallydisclosed herein.

What is claimed is:
 1. A woven stretch fabric for reinforcing a powertransmission belt comprising textured staple fibers of polyarylenesulfide.
 2. The fabric of claim 1 comprising warp and weft threads,wherein at least one of said warp and weft threads comprises said staplefibers of polyarylene sulfide in the form of a textured staple yarn ofpoly p-phenylene sulfide fibers.
 3. The fabric of claim 2 wherein saidpoly p-phenylene sulfide fibers are present in the weft and textured tohave at least 50% elongation at 2 kg tension, and said warp comprisestextured polyamide fiber.
 4. The fabric of claim 3 wherein said fabricfurther comprises as said textured polyamide fiber nylon-66 fiberstextured to have from 1 to 20% elongation at 2 kg tension, and whereinsaid fabric has no elastic core thread.
 5. A power transmission belthaving an elastomeric body, a tensile member embedded within said body,a pulley contact surface, and a back surface; comprising on at least oneof said surfaces a woven stretch fabric comprising textured staplefibers of polyarylene sulfide.
 6. The belt of claim 5 in the form of atoothed belt having teeth on said pulley contact surface and with saidfabric covering said teeth.
 7. The belt of claim 5 wherein said fabricis woven with transverse and longitudinal threads with respect to theirorientation in the belt, and wherein said transverse threads comprisenylon-66 fibers, and said longitudinal threads comprise both texturednylon-66 fibers and said polyarylene sulfide fibers in the form of polyp-phenylene sulfide fibers.
 8. The belt of claim 7 wherein saidtransverse threads are textured to achieve from 1% to 20% elongation at2 kg tension, and said longitudinal threads are textured to achieve atleast 50% elongation at 2 kg tension.
 9. The belt of claim 7 whereinsaid longitudinal threads comprise no elastic core.
 10. A powertransmission belt reinforced with a woven stretch fabric comprisinglongitudinal yarns oriented in the belt longitudinal direction that arecapable of stretching at least about 50% and transverse yarns orientedin the belt transverse direction; with the longitudinal yarns comprisingpolyamide fibers and staple fibers of polyarylene sulfide; and thetransverse yarns consisting of textured multifilament polyamide yarn.11. The belt of claim 10 wherein the longitudinal yarns are textured toachieve said stretching capability.
 12. The belt of claim 10 wherein thetransverse yarns are textured to achieve the capability of stretching inthe range of from about 1% to about 20%.
 13. The belt of claim 12 in theform of a toothed power transmission belt.
 14. The belt of claim 10wherein the transverse yarns are textured to achieve the capability ofstretching in the range of from about 2% to about 10% under 2 kgtension, and said longitudinal yarns are capable of stretching at leastabout 80%.